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Add hamming distance function

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This commit is contained in:
Dimitri Lozeve 2020-06-03 22:15:57 +02:00
parent 55fba9cfd2
commit 886f1d45cb
5 changed files with 123 additions and 0 deletions
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29
utils.c
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@ -3,6 +3,20 @@
#include <math.h>
#include <string.h>
#define min(a, b) \
({ \
__typeof__(a) _a = (a); \
__typeof__(b) _b = (b); \
_a > _b ? _b : _a; \
})
#define max(a, b) \
({ \
__typeof__(a) _a = (a); \
__typeof__(b) _b = (b); \
_a > _b ? _a : _b; \
})
unsigned char hex_to_byte(const char c) {
if (isdigit(c)) {
return c - '0';
@ -69,3 +83,18 @@ double frequency_score(unsigned char *buf, size_t len) {
}
return chi2;
}
unsigned int hamming(const char *s1, const char *s2) {
unsigned int len1 = strlen(s1);
unsigned int len2 = strlen(s2);
unsigned int res = 0;
for (size_t i = 0; i < min(len1, len2); ++i) {
unsigned int n = s1[i] ^ s2[i];
while (n) {
res += n & 1;
n >>= 1;
}
}
return res;
}